Measuring characteristics of TCP connections at Internet scale

This post shares aggregate insights about TCP connection characteristics observed through Cloudflare's global CDN. It details the methodology for collecting and analyzing socket-level metadata from the Linux kernel's TCP_INFO struct, focusing on connections that close gracefully with a FIN packet and have at least one successful HTTP request. The analysis presents empirical data on packet counts (response packets, and packet ratios between client and server) and bytes sent, highlighting the heavy-tailed nature of internet traffic and differences across HTTP protocol versions. This data is intended to inform simulations and provide a deeper understanding of real-world network behavior.